This invention generally relates to the fabrication of teeth for an agricultural spike-toothed harrow implement and, particularly, to a cold formed spike harrow tooth.
Agricultural spike-toothed harrow implements conventionally include a series of generally parallel, interconnected support bars extending transversely to the direction in which the implement is moved across the ground. Spike harrow teeth are mounted on and project downwardly from the support bars at spaced intervals for working the soil. Conventionally, the teeth are assembled to the support bars by dropping the teeth point-first through holes in the bars, with the teeth having enlarged heads to prevent the teeth from falling completely through the holes. Securing means, such as U-bolts, embrace the teeth and secure the teeth to the support bars, allowing for vertical adjustment of the effective working length of the teeth. Such assemblies not only provide for easy original assembly of the harrow implement, but ready replacement of worn or broken harrow teeth is afforded.
The most prevalent method of fabricating spike harrow teeth of the character described comprises a series of steps involving a hot forming process which is relatively expensive and time consuming. The process starts with hot rolled bar stock usually of square cross-sectional configuration, which is cut at ambient temperature to lengths or blanks which are double the length of a single harrow tooth. The double-length blank then is placed into an oven or furnace to heat only opposite ends of the blank in a localized heating manner. The heated blank then is confined and the ends are hot formed in an inwardly axial direction to form enlarged heads at opposite ends of the double-length blank. The blank then is fed into another oven or furnace which heats only the center of the blank in a localized heating manner. The blank then is hot-formed by drawing the ends of the blank in opposite directions to form opposed points, eventually separating the double-length blank into two individual harrow teeth. The hot teeth are quenched in cooling medium such as water.
The above hot-forming process has been deemed necessary because of the desirability of using metal bar stock of grade C-1045 carbon steel, or the like such as in the range of C-1035 to C-1090. It was believed that such steel would have longer wear, particularly when quenched at the end of the manufacturing process.
It is readily apparent that the above process is quite expensive and time consuming because of the number of steps involved, in addition to the heat expense itself. Other problems also have been encountered in being able to manufacture harrow teeth of consistent configuration. This is important to the ultimate consumer, particularly when replacing worn or damaged harrow teeth in existing agricultural implements. For instance, the amount and/or concentration of heat can actually determine the shape of the harrow teeth points.
It has been found by the instant invention that consistent, substantially identical harrow teeth can be formed by a cold process which is considerably less expensive, eliminating the problems described above, and still using metal such as grade C-1045 carbon steel. Consequently, this invention is directed to the fabrication of spike harrow teeth of the character described in a new and improved cost effective process which eliminates many of the problems described above.